go aft
My 28.5 was recently fitted with a bimini by UK sails of New Orleans. It extends from aft of the main about 1 foot ABOVE the boom several feet aft( total fore-aft distance of 7 feet. We have sailed all summer with the new bimini and the helm is always in the shade while affording the remainder of the people in cockpit sunlight( or shade if they want to sit next to me) This set up is far superior to the old bimini I had on the boat which covered the whole cockpit since 1) I can stand at the helm 2) the main can be properly trimmed while going to weather 3) the boom does not touch the bimini 4)I can see the main easily while sailing 5) since the mounts are about 6 inches from the stern of the boat the bimini really never gets in the way. The split backstay and and adjuster have appropriate cut outs. Cost--650.00 but well worth it since all tubing is heavy stainless, all chafe points covered in leather, and they only use gore-tex thread to sew with. I'm sure it will last at least twice as long as biminis that cost more than half as much.